Driving workload estimation

ABSTRACT

A method for estimating workload placed on the driver of a vehicle. The method comprises receiving workload estimation data. A driving workload estimate is calculated in response to the workload estimation data. The driving workload estimate is indicative of current and previously occurring conditions. The driving workload estimate is then output.

BACKGROUND OF THE INVENTION

[0001] The present disclosure relates generally to driving workloadestimation and in particular, to a method of assessing the marginaleffect of vehicle conditions, environment conditions and current taskconditions on the driver of a vehicle.

[0002] Vehicles, such as automobiles, generally feature one or moredisplays to provide locally obtained information related to a currentstate of the vehicle. The display is positioned within the vehicle suchthat a driver of the vehicle may view information while driving thevehicle. For example, the display may provide information on awindshield, a dashboard or a steering wheel. Each display may containone or more windows. Locally obtained information, such as the speed ofthe vehicle, the direction traveled by the vehicle, the outside airtemperature, whether the air conditioner is in use, whether the hazardlight is on, fuel status of the vehicle, and the like, may be providedin these windows. In addition, information can be collected from vehiclesensors and used to create vehicle status and maintenance messages fordisplay in the windows. These messages can include information such as“window washer fluid low” and “check tire pressure.”

[0003] The current displays in vehicles are capable of providingdifferent types of media from a variety of sources. The display mayprovide audio, text, graphic images, and/or video (e.g., night visiondisplay). Additionally, the display may provide information from variousdatabases and remote servers using a wireless network. For example,traffic and/or weather alerts may be communicated through any of thedisplay means mentioned above. In addition, smart advertising may betransmitted to the display to inform the driver of a nearby restaurantor store. Providing all of these types of information and media may behelpful to the driver but providing it without considering the currentdriving situation may result in increased driver workload, driverdistraction and/or decreased driving performance.

BRIEF DESCRIPTION OF THE INVENTION

[0004] The above discussed and other drawbacks and deficiencies of theprior art are overcome or alleviated by a method for estimating workloadplaced on the driver of a vehicle. In an exemplary embodiment, themethod comprises receiving workload estimation data. A driving workloadestimate is calculated in response to the workload estimation data. Thedriving workload estimate is indicative of current and previouslyoccurring conditions. The driving workload estimate is then output.

[0005] In another aspect, a system for estimating workload placed on thedriver of a vehicle comprises a network and a microprocessor incommunication with the network. The microprocessor includes instructionsto implement a method. The method comprises receiving workloadestimation data from the network. A driving workload estimate iscalculated in response to the workload estimation data. The drivingworkload is indicative of current and previously occurring conditions.The driving workload estimate is then output.

[0006] In still another aspect, a computer program product forestimating workload placed on the driver of a vehicle comprises astorage medium readable by a processing circuit and storing instructionsfor execution by the processing circuit for performing a method. Themethod comprises receiving workload estimation data. A driving workloadestimate is calculated in response to the workload estimation data. Thedriving workload estimate is indicative of current and previouslyoccurring conditions. The driving workload estimate is then output.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Referring to the exemplary drawings wherein like elements arenumbered alike in the several FIGURES:

[0008]FIG. 1 is a block diagram of an exemplary system for performingdriving workload estimation;

[0009]FIG. 2 is a table of exemplary driving workload estimate inputs;and

[0010]FIG. 3 is a table of logical operands associated with drivingworkload estimation in an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Disclosed herein is a method of driving workload estimation.Briefly stated, the method utilizes vehicle data, environment data andcurrent task data to estimate the workload placed on the vehicle driver.A conditional model of the driver's workload (herein identified asdriving workload) is developed by assessing the marginal effect of thevehicle, environment and current tasks on the driver. Multiple levels orstates of the driving workload are estimated by workload estimationsoftware. In an exemplary embodiment, the estimated workload statesinclude an instantaneous workload estimate, an intermediate workloadestimate and an overall workload estimate. Alternatively, the system canutilize a single workload estimate, provided that some method ofaccounting for the lingering impact of events and conditions that are nolonger occurring is taken into account by the workload estimate. Theseestimated workload states are output and can be sent to a vehicleinformation management system to aid in controlling the messages beingsent and the functionality available to the operator of the vehicle.

[0012]FIG. 1 is a block diagram of an exemplary system for performingdriving workload estimation. Vehicle data 104, environment data 106 andcurrent task data 108 are input to a driving workload estimator 102. Thedriving workload estimator 102 includes application code for creating aninstantaneous workload estimate 110, an intermediate workload estimate112 and an overall workload estimate 114. In an exemplary embodiment,the driving workload estimator 102 is located on a microprocessorcontained in the vehicle. The microprocessor may be dedicated toperforming driving workload estimator 102 functions or, alternatively,the microprocessor may include application code for performing othervehicle functions along with the driving workload estimator 102functions. In addition, storage space for intermediate applicationresults as well as application inputs and outputs can be located on themicroprocessor or located on an external storage device accessible bythe microprocessor.

[0013] Vehicle data 104 is internally generated and is received fromsensors located inside the vehicle. Vehicle data 104 can includeinformation such as vehicle speed, cruise control state, turn signalstatus, traction control status (TCS), antilock braking system (ABS)status, vehicle stability system data, powertrain data, steering wheelangle, brake pedal position and throttle pedal position data. Powertraindata can include information such as revolutions per minute (RPM), sparkdata and fuel data. Environment data 106 can include external lightsensor/headlamp status data, wiper status, defroster status, outside airtemperature (OAT), global positioning system (GPS) data, time of day,and enhanced digital maps. Current task data 108 includes data such asradio information (e.g., is manipulation occurring) and phoneinformation (e.g., is the phone active). In addition, driveridentification input to the driving workload estimator 102 can be usedto tailor the workload estimates to a particular driver of the vehicle.Additional input can include driver monitoring data and input that isscalable to the vehicle sensor set and the equipment package (e.g.,navigation, imbedded cell phone). Driver monitoring data includes theability for the driver, or the vehicle system to revise the drivingworkload estimate. Additional input data can also include informationfrom an object detection and warning and/or lane sensing application orsensor. Examples include forward collision warning (FCW) data, sideobject detection (SOD) data, lane departure warning (LDW) data and rearcollision warning (RCW) data. Further input to the driving workloadestimator 102 can include infotainment and telematics system status;speech interface status and diagnostics data; and adaptive cruisecontrol (ACC) system data.

[0014] The specific inputs to the driving workload estimator 102 canvary between implementations depending on the input data available in aparticular vehicle and the requirements of a particular implementation.A network can be used to obtain the data and the network can be internalto the vehicle or the network can provide access to information outsidethe vehicle. Any information that can be sensed, measured or inputthrough an interface (e.g., wireless network) can be used as input tothe driving workload estimator 102. Environment data 106 can be expandedto include information such as vehicle location data; external vehiclelocation data; traffic information both present and predicted; andweather information both present and predicted. As depicted in FIG. 1,three workload estimates are output from the driving workload estimator102. The workload estimates are updated on a periodic basis and includenumeric values that reflect relative workload levels. The workloadestimate can be relative to a starting state such as clear driving atnormal speed or driver workload when the vehicle is stationary. In analternate embodiment, data in addition to the numeric values may beincluded in the workload estimates.

[0015] The instantaneous workload estimate 110 is based on a short-termtime frame (e.g., the preceding zero to three seconds). For example, aturn signal coupled with a particular steering wheel angle may indicatethat the vehicle is turning. The act of turning would have an impact onthe instantaneous workload because it will add to the current drivingworkload and is generally completed in a few seconds. The intermediateworkload estimate 112 is a workload based on an intermediate timeinterval (e.g., twenty seconds to one minute, three seconds to threeminutes, three seconds to ten minutes). The intermediate workloadestimation will carry a declining balance input on workload estimatesfor recent events. For example, if the input data indicates that thedriver has just merged into traffic or that the ABS brake system isactivated, the intermediate workload estimate 112 would reflect theseevents for a specified intermediate time interval. This may beimplemented by having the estimator initiate a sub-routine that causesthe workload estimate to remain above the starting state due to the factthat the effect of an ABS event does not end as soon as the ABS stopsbeing activated. An event that affects the intermediate workloadestimate 112 includes some recovery time for the driver and this isreflected in the length of time that the workload estimate continues toreflect the occurrence of the event.

[0016] The overall workload estimate 114 includes long term workload ortotal workload accumulated during an ignition cycle (e.g., from threeminutes and up, ten minutes and up, entire ignition cycle). For example,the length of time that the driver has been operating the vehicle can befactored into the overall workload estimate 114. In an exemplaryembodiment, each workload estimate is associated with from three to onehundred workload level values. In an alternate embodiment, hundreds orthousands of workload level values may be associated with each workloadestimate.

[0017] The input data depicted in FIG. 2 can be utilized by a drivingworkload estimator 102 to calculate the driving workload estimate as afunction of vehicle data 104, environment data 106 and current task data108. Referring to the vehicle data 104 in FIG. 2, the value of vehiclespeed 202 can be calculated based on the current speed of the vehicleand whether the driver is accelerating or decelerating. The value ofturn signal status 204 can be determined based on whether the turnsignal is activated. The value of ABS/TCS/ stability system data 206 canbe calculated from sensor data gathered from dynamic vehicle controlssuch as the wheel speed sensors. The steering wheel angle data 208 isdetermined by sensors capable of determining the rate of vehicleturning. Brake and throttle pedal position data 210 can be determined bythe data gathered from sensors such as the throttle position sensor(TPS) and brake pedal switch or sensor. The value of engineRPM/spark/fuel data 212 (powertrain data) can be calculated from enginemanagement sensors and data (e.g., the TPS).

[0018] Referring to the inputs relating to environment data 106 in FIG.2, the value of headlamp status 214 can be determined by either theexternal light sensor or by data from the headlamp controls. The valueof wiper status 216 can be determined by either a rain sensor or thewiper controls. The value of defroster status 218 can be determined bythe defroster controls. The outside air temperature (OAT) data 220 canbe determined by a sensor dedicated to that purpose. Global positioningdata 222 is determined by accessing data from the global positioningsystem within the vehicle network. Time of day 224 is determined fromthe clock data within the vehicle. Referring to the inputs relating tocurrent task data 108 in FIG. 2, radio information 226 is determined byaccessing vehicle data regarding radio feature and function activity.Phone status 228 is determined by accessing existing vehicle datapertaining to an integrated cellular phone system. The values associatedwith the input data in FIG. 2 is input to a function. The function islocated in the driving workload estimator 102 and it utilizes the inputdata to determine the instantaneous workload estimate 110, theintermediate workload estimate 112 and the overall workload estimate114.

[0019]FIG. 3 is a table of logical operands associated with drivingworkload estimation for use by a function to calculate a drivingworkload estimate in an exemplary embodiment of the present invention.The logical operands are used to create a framework and to set initialweightings of the driving workload estimation and can be modified tofine tune the driving workload estimator 102. A workload estimate iscalculated to reflect an instantaneous workload estimate 110, anintermediate workload estimate 112 and an overall workload estimate 114based on assigning numeric values to each of the conditions depicted inFIG. 3. Numeric values and inputs can be the same for all three workloadestimates or they can vary. As shown in FIG. 3, the value of therelative workload effect associated with vehicle speed 202 can becalculated by assigning a numeric value to the results of applying thevehicle speed equations 302. A vehicle traveling between twenty milesper hour and fifty miles per hour can be given a higher speed value thana car traveling between zero miles per hour and twenty miles per hour.Similarly, a vehicle traveling between fifty miles per hour and seventymiles per hour can be given a higher speed value than a car travelingbetween twenty miles per hour and fifty miles per hour. A vehicletraveling over seventy miles per hour can be given a higher speed valuethan a car traveling between fifty miles per hour and seventy miles perhour. The value of the relative workload for turn signal status 204 canbe calculated by assigning a higher numeric value if the turn signal isactivated than if the turn signal is not activated, as reflected in theturn signal status equations 304. As shown in the ABS/TCS/stabilityequations 306, situations where the ABS, TCS and/or vehicle stabilitysystem are active can be given a higher value than when they are not.

[0020] Referring to FIG. 3, the value of the relative workload forexternal conditions including headlamp status 214, wiper status 216,outside air temperature 220 and time of day 224 can be calculated byassigning numeric values to the results of applying the correspondingequations. Night can be given a higher relative value than day asreflected in the headlamp status equations 308, precipitation can begiven a higher relative value than no precipitation and snow can begiven a higher numeric value than rain as reflected in the wiper statusequations 310 and the outside air temperature equations 312. Therelative value associated with time of day 224, as reflected in the timeof day equations 314, can be calculated by assigning higher numericvalues as the current time gets further away from noon and closer tomidnight. In an alternate embodiment, the value for time of day can becalculated as a sinusoidal cycle with the peak weighting from elevenp.m. to one a.m. and the baseline from noon to one p.m. The relativevalue associated with the radio information 226 can be calculated usingthe radio task data equations 316 where the act of manipulating theradio is given a higher relative value than when no radio manipulationis taking place. Similarly, the relative workload value associated withphone status 228 can be calculated by assigning a higher relative valueto phone dialing and conversations than to the absence of phoneactivity. This is reflected in the phone status equations 318.

[0021] In an alternate embodiment of the present invention, informationfrom more than one input is utilized to create the workload estimates.For example, the workload estimate can take into account snowy roads ifthe temperature is below freezing and the windshield wipers are turnedon. Additionally, if the ABS brake system is activated then the estimatecan take into account the road conditions associated with snowy roads.These kinds of cross grouping combinations can lead to a better estimateof the driver workload. The time span that each value continues to becounted towards a driving workload estimate can depend on whether theworkload estimate is an instantaneous workload estimate 110, anintermediate workload estimate 112 or an overall workload estimate 114.For example, the function to calculate an intermediate workload estimate112 would continue to count the use of ABS or TCS for a specified periodof time (e.g., twenty seconds to one minute) while the function tocalculate the instantaneous workload estimate 110 would count the use ofABS or TCS for a shorter period of time (e.g., zero to three seconds).In this manner, the three types of workload estimates are created usingfunctions that weight the values assigned to the inequalities over aspecified time span. The resulting instantaneous workload estimate 110,intermediate workload estimate 112 and overall workload estimate 114 arethen output from the driving workload estimator 102. The output caninclude transmission to a specified location and logging to a specifiedlocation.

[0022] The disclosed invention provides the ability to estimate theworkload that a driver is experiencing using data that is alreadyavailable within a vehicle. Vehicle data, environment data and currenttask data can be used to create inferences about the driver's currentstate (i.e., instantaneous workload estimate), short term state (i.e.,intermediate workload estimate) and long term state (i.e., overallworkload estimate). The workload estimates can be utilized by displayfunctions and controls within the vehicle to determine the timing ofparticular messages and when to enable or disable particular functions.For example, a message to rotate the tires can be presented to theoperator of the vehicle when the workload estimate is on the low sideand the operator is more likely to be able to process the information.Having three time spans for the workload estimates provides the abilityto track the longer term effects of particular workload estimateelements. The ability to predict the driving workload simultaneously fordifferent time spans can lead to better estimates of the drivingconditions and driver's state, resulting in better communication betweendriver and vehicle. Additionally, this informed interface maypotentially result in higher driver satisfaction with the vehicle and/orsafer vehicle operation.

[0023] As described above, the embodiments of the invention may beembodied in the form of computer-implemented processes and apparatusesfor practicing those processes. Embodiments of the invention may also beembodied in the form of computer program code containing instructionsembodied in tangible media, such as floppy diskettes, CD-ROMs, harddrives, or any other computer-readable storage medium, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Anembodiment of the present invention can also be embodied in the form ofcomputer program code, for example, whether stored in a storage medium,loaded into and/or executed by a computer, or transmitted over sometransmission medium, such as over electrical wiring or cabling, throughfiber optics, or via electromagnetic radiation, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Whenimplemented on a general-purpose microprocessor, the computer programcode segments configure the microprocessor to create specific logiccircuits.

[0024] While the invention has been described with reference toexemplary embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, the use of the terms first, second, etc. do not denoteany order or importance, but rather the terms first, second, etc. areused to distinguish one element from another.

What is claimed is:
 1. A method for estimating workload placed on thedriver of a vehicle, the method comprising: receiving workloadestimation data; calculating a driving workload estimate in response tosaid workload estimation data, said driving workload estimate beingindicative of current and previously occurring conditions; andoutputting said driving workload estimate.
 2. The method of claim 1wherein said workload estimation data includes internally generatedvehicle data.
 3. The method of claim 1 wherein said workload estimationdata includes environment data.
 4. The method of claim 1 wherein saidworkload estimation data includes current task data.
 5. The method ofclaim 1 wherein said driving workload estimate includes an instantaneousworkload estimate.
 6. The method of claim 5 wherein said instantaneousworkload estimate reflects the previous zero to three seconds of vehicleoperation.
 7. The method of claim 1 wherein said driving workloadestimate includes an intermediate workload estimate.
 8. The method ofclaim 7 wherein said intermediate workload estimate reflects theprevious three seconds to three minutes of vehicle operation.
 9. Themethod of claim 1 wherein said driving workload estimate includes anoverall workload estimate.
 10. The method of claim 9 wherein saidoverall workload estimate reflects vehicle operation for the entireignition cycle.
 11. The method of claim 1 wherein said driving workloadestimate is expressed as a number ranging from one to ten.
 12. Themethod of claim 1 wherein said driving workload estimate is expressed asa number ranging from one to one-hundred.
 13. The method of claim 1wherein said calculating a driving workload estimate includes: assigningan instantaneous value to at least one of said workload estimation data;applying an instantaneous workload function, wherein input to saidinstantaneous workload function includes each said instantaneous valueand said applying results in an instantaneous workload estimate;assigning an intermediate value to at least one of said workloadestimation data; applying an intermediate workload function, whereininput to said intermediate workload function includes each saidintermediate value and said applying results in an intermediate workloadestimate; assigning an overall value to at least one of said workloadestimation data; and applying an overall workload function, whereininput to said overall workload function includes each said overall valueand said applying results in an overall workload estimate.
 14. Themethod of claim 1 wherein said outputting includes transmitting saiddriving workload estimate to a specified location.
 15. The method ofclaim 14 wherein said specified location is a vehicle informationmanagement system.
 16. The method of claim 1 wherein said outputtingincludes writing said driving workload estimate to a log file.
 17. Themethod of claim 1 wherein said outputting is performed on a periodicbasis.
 18. The method of claim 17 wherein said periodic basis less thanone second.
 19. The method of claim 1 wherein said workload estimationdata includes at least one of vehicle speed, turn signal status,anti-lock brake status, traction control system status, vehiclestability data, steering wheel angle data, brake position data, throttleposition data, engine revolutions per minute, spark data and fuel data.20. The method of claim 1 wherein said workload estimation data includesat least one of headlamp status, wiper status, defroster status, outsideair temperature data, global positioning data and time of day.
 21. Themethod of claim 1 wherein said workload estimation data includes atleast one of radio information and phone status.
 22. The method of claim1 wherein said workload estimation data includes adaptive cruise controldata.
 23. The method of claim 1 wherein said workload estimation dataincludes at least one of forward collision warning data, side objectdetection data and rear collision warning data.
 24. The method of claim1 wherein said workload estimation data includes lane departure warningdata.
 25. The method of claim 1 wherein said workload estimation dataincludes driver identification data.
 26. A system for estimatingworkload placed on the driver of a vehicle, the system comprising: anetwork; and a microprocessor in communication with said network, saidmicroprocessor including instructions to implement the methodcomprising: receiving workload estimation data from said network;calculating a driving workload estimate in response to said workloadestimation data, said driving workload estimate indicative of currentand previously occurring conditions; and outputting said drivingworkload estimate.
 27. The system of claim 26 further comprising avehicle sensor in communication with said network for creating saidworkload estimation data.
 28. The system of claim 26 wherein saidnetwork is the Internet.
 29. The system of claim 26 wherein said networkis a wireless network.
 30. The system of claim 26 wherein saidoutputting said driving workload estimate includes transmitting saiddriving workload estimate to a receiving location over said network. 31.A computer program product for estimating workload placed on the driverof a vehicle, the product comprising: a storage medium readable by aprocessing circuit and storing instructions for execution by theprocessing circuit for performing a method comprising: receivingworkload estimation data; calculating a driving workload estimate inresponse to said workload estimation data, said driving workloadestimate indicative of current and previously occurring conditions; andoutputting said driving workload estimate.